1. Field of Invention
The present invention relates to a electronic optical device, a projection type device using the same, and a method for producing the electronic optical device. In more detail, the present invention relates to a construction technology of the outer face of the two sheets of transparent substrates inside of which a liquid crystal is disposed, and a technology for forming the construction.
2. Description of Related Art
As shown in FIG. 16, the electronic optical device is mainly composed of an active matrix substrate 300 (a first transparent substrate) on which pixel electrodes and pixel switching elements are formed, an opposite substrate 400 (a second transparent substrate) on which opposite electrodes are formed, and one example of a electronic optical material, a liquid crystal (LC) disposed between the active matrix substrate 300 and opposite substrate 400. The liquid crystal (LC) is filled in the area divided by the substrates with a seal layer 80 between the active matrix substrate 300 and the opposite substrate 400. Alignment of the liquid crystal is controlled for each pixel between the active matrix substrate 300 and the opposite substrate 400.
Accordingly, in the projection type device in which a electronic optical device having a construction as described above is used as a light valve, the light projected from a light source is condensed by a condenser optical system to guide the light to the electronic optical device and a desired image is projected with magnification on a projection plane such as a screen by a magnifying projection optical system after optically modulating the projected light with the electronic optical device.
Although the electronic optical device constructed as described above is usually mounted in a light-shielding case provided with an opening corresponding to the display area, contours of the display area are usually defined by the light-shielding film (referred to as a partitioning periphery hereinafter) made of Cr (chromium) and the like on the opposite substrate 400. In other words, a design margin at the opening of the case is ensured by the width of the partitioning periphery since it is difficult for the edge of the opening of the case formed of a plastic and the like to have a sufficient dimensional accuracy due to the presence of burrs at the edge. According to this art, problems that the display area is hidden behind the opening of the case or the panel portion outside of the display area at the outer circumference of the partitioning periphery is exposed from the opening can be avoided when the opening of the case is formed with an accuracy enough for accommodating the opening of the case within the width of the partitioning periphery viewed from the front of the display area.
However, since the outer face 302 of the active matrix substrate 300 or the outer face 402 of the opposite substrate electrode 400 is only separated by the thickness of these transparent substrates, for example 1 mm, when viewed from the liquid crystal (LC), the light focusing on the liquid crystal (LC) is also focusing on flaws and dust adhered on the outer face of these transparent substrates. Consequently, flaws and dust as small as 10 to 20 xcexcm are displayed in the projection image, deteriorating the image quality.
A partial temperature increase is liable to occur as a result of making the thickness of the active matrix substrate 300 and the opposite substrate 400 thin, because an intense light is illuminated from the light source to the electronic optical device in the projection type device The partial heated portion has a different transmittance from that of the surrounding area, thereby also deteriorating the image quality. Such partial temperature increase may be a cause to deteriorate the liquid crystal.
Japanese Unexamined Patent Publications No. 9-105901 and No. 9-113906 have proposed a construction as shown in FIG. 17, wherein a transparent substrate 102 is attached on the outer face 302 of the active matrix substrate 300 via an air layer (air) using a bonding material 101, thereby suppressing a temperature increase of the electronic optical device by heat radiation from this transparent substrate 102 along with preventing flaws and dust from adhering on the outer face 302 of the active matrix substrate 300 owing to this transparent substrate 102. However, boundary faces between the active matrix substrate 300 and the air layer, and between the air layer (air) and the transparent substrate 102 are added as new reflection boundary faces as a consequence of disposing the opposite transparent substrate 102 on the outer face 302 of the active matrix substrate 300 via an air layer (air) in the electronic optical device having the construction shown in FIG. 17, thereby increasing reflection at the boundary face. Accordingly, luminous energy loss is increased to cause a new problem that the projected image becomes dark in the electronic optical device with the construction shown in FIG. 17. While it may be devised that a reflection preventing film is deposited in vacuum on the outer face 302 of the active matrix substrate 300 and on the inner face 104 of the transparent substrate 102, forming such reflection preventing films requires much labor in a vacuum atmosphere, resulting in a large increase of the production cost of the electronic optical device. Disposing only a transparent substrate 102 on the outer face 302 of the active matrix substrate 300 cannot yet prevent dust from adhering on the outer face 302 of the active matrix substrate 300. Consequently it has been impossible to perfectly prevent the display image quality from being deteriorated.
As hitherto described, there is a first problem that the dust-preventive function, de-focusing function and heat radiation function cannot be improved at once with a low production cost and good balance in the conventional electronic optical device.
In the field of current electronic optical devices, on the other hand, demands for making the panel small and fine, or demands for ensuring a large display area in a limited panel face have been increasing, forcing the necessity to narrow the width of the partitioning periphery provided at the opposite substrate as described previously. The width of the partitioning periphery is also required to be narrow, especially in adhering both substrates with an adhesive comprising an ultraviolet light curing type resin, so as not to block ultraviolet light irradiation from the outer face of the substrate because the seal area for bonding both substrates with an adhesive exists in the vicinity of the partitioning periphery. Consequently, there arises a second problem that the design margin at the opening portion of the case is reduced as the width of the partitioning periphery is narrowed in the art for ensuring the design margin of the opening portion of the case by using the width of the partitioning periphery.
Furthermore, there arises another problem that ghost images of the auxiliary circuits and elements provided in the panel are mixed with the projecting light depending on the angle of the incident light and projecting light, when the electronic optical device provided with the partitioning periphery is used for the projection type display device and the transmissive display device provided with a back light, especially when the width of the partitioning periphery is narrowed.
Accordingly, an object of the present invention is to solve the foregoing first problem, by providing a electronic optical device with a high image quality and a projection type device using the same, wherein flaws and dust are prevented from adhering on the transparent substrates, between which a liquid crystal is inserted, without significantly increasing the production cost by improving the construction of the outer faces of two sheets of transparent substrates for disposing a liquid crystal, along with suppressing temperature increase ascribed to irradiation of light from the light source.
Another object of the present invention is to provide a method for producing electronic optical devices capable of producing such electronic optical devices with a high quality.
Another object of the present invention is to solve the foregoing second problem, providing a electronic optical device in which the design margin of the opening portion of the case can be enlarged while enhancing the dust preventive function against dust and defocusing function against dust and flaws, and a projection type device provided with the same.
For solving the problems described above, the present invention provides a electronic optical device having a first transparent substrate on which pixel electrodes are formed, a second transparent substrate opposing the first transparent substrate and a liquid crystal disposed between the first and second transparent substrates. A planar surface of a third transparent substrate having an approximately equal refractive index to at least one of the first and second transparent substrates is adhered to an outer surface of at least one of the first transparent substrate and the second transparent substrate with an adhesive that has an approximately equal reflection index to at least one of the transparent substrates.
In the specification according to the present invention, an inner surface refers to a surface at the side where the liquid crystal is situated, while the outer surface refers to a surface at an opposite side where the liquid crystal is situated, of the both surfaces of the transparent substrate.
Flaws and dust are hardly adhered on the outer surface of the first or second transparent substrate in the electronic optical device constructed as described above, since the planar surface of the third transparent substrate is adhered to the outer surfaces of the two sheets of the transparent substrates (the first and second transparent substrates) forced to be positioned in the vicinity of the liquid crystal because the liquid crystal is inserted between them. The outer surface of the third transparent substrate is always de-focused because a distance corresponding to the thickness of this third transparent substrate is maintained between the outer surface of the third transparent substrate and the liquid crystal. The image quality becomes high because flaws and dust are never displayed on the projection image even when flaws and dust are adhered on the outer surface of the third transparent substrate.
No reflection boundary face is considered to be present in the spaces between the first or second transparent substrate and the adhesive and between the adhesive and the third transparent substrate, since both of the adhesive and the third transparent substrate have an approximately equal refractive index to the refractive index of the substrates on which the third transparent substrate is adhered. Accordingly, the light guided from the light source efficiently transmits through the electronic optical device, resulting in a very small luminous energy loss. Increase of the production cost can be therefore suppressed because forming reflection preventive films between each transparent substrate and the adhesive is not required. There is also an advantage that the chances of switching elements malfunctioning due to this reflection light can be excluded. Moreover, since the adhesive has a refractive index approximately equal to the refractive index of the first or second transparent substrate on which the adhesive is coated, flaws generated on the first or second transparent substrate in the production process of the electronic optical device are buried with the adhesive that is used to restore the flaws.
The electronic optical device has a larger heat capacity corresponding to the addition of the third transparent substrate. Accordingly, temperature increase in the electronic optical device remains small with no partial temperature increase, preventing dispersion of the transmittance and deterioration of the liquid crystal due to temperature difference and thereby improving the image quality.
When the planar surface of the third transparent substrate is adhered to the outer surface of the first transparent substrate in the present invention, a film having a light polarizing function or a reflection preventing function may be laminated on the outer surface of at least one of the third and the second transparent substrates. On the contrary, when the planar surface of the third transparent substrate is adhered on the outer surface of the second transparent substrate, a film having a polarizer function or a reflection preventing function may be laminated on the outer surface of at least one of the third and the first transparent substrates. Further, when the planar surface of the third transparent substrates are adhered on both of the outer surfaces of the first transparent substrate and second transparent substrate, a film having a polarizer function or a reflection preventing function may be laminated on the outer surface of at least one of the two sheets of the third transparent substrates.
It is preferable in the present invention that the adhesive remains elastic after being cured. In this construction, stress accompanied by curing the adhesive can be relaxed by the adhesive itself, leaving no distortion on the transparent substrate. For example, when the degree of penetration of the adhesive after being cured is larger than 60 and smaller than 90, distortion of the transparent substrate can be prevented from being generated along with relaxing the stress. The thickness of the adhesive is preferably 5 to 30 xcexcm. A thickness of at least 5 xcexcm allows the flaws adhered on the substrate to be covered with the adhesive as well as relaxing the stress.
Flaws and dust adhered on the transparent substrate never deteriorate the image quality in the electronic optical device constructed as described above, which is suitable for use in the projection type device having a light source, a condenser optical system that condenses the light projected from the light source to guide it to the electronic optical device, and a magnifying projection optical system that projects the light optically modulated with the electronic optical device on a projection plane with magnification. While the image quality tends to be deteriorated by the influence of the flaws and dust adhered on the transparent substrate because the image is projected with magnification in this type of the electronic optical device, these problems can be solved when the electronic optical device to which the present invention is applied is used. While an intense light from the light source is illuminated in the projection type device, failures due to the temperature increase can be avoided from occurring by using the electronic optical device to which the present invention is applied even when such an intense light is irradiated.
It is preferable in the method for producing the electronic optical device according to the present invention comprising the step for adhering the planar surface of the third transparent substrate that, after coating both surfaces of the inner surface of the third transparent substrate and the outer surface of the transparent substrate on which the planar surface of the third transparent substrate is adhered with the adhesive before curing it, the adhesive is spread by joining two sheets of the transparent substrates together by taking advantage of these adhesives on both surfaces as a primary contact point, followed by curing the adhesive.
It is preferable in the method for producing the electronic optical device according to the present invention comprising the step for adhering the planar surface of the third transparent substrate that, after surrounding the periphery of the area, of the spaces between the third transparent substrate and the transparent substrate on the outer surface of which the planar surface of the third transparent substrate is adhered, where the adhesive is to be coated with a seal material provided with a partial cut-off portion as an injecting port of the adhesive, the area divided with the seal material is evacuated of air to inject the adhesive in vacuum from the adhesive port into the area, followed by curing the adhesive.
According to the production method, the planar surface of the third transparent substrate can be adhered without leaving any air bubbles in the adhesive.
It is preferable that solid gap materials for keeping the thickness of the adhesive layer constant are added in the seal material.
For solving the problems previously described, the electronic optical device provides a electronic optical device provided with a first transparent substrate in which pixel electrodes are formed on the display area; a second transparent substrate opposing the first transparent substrate; a liquid crystal disposed between the second transparent substrate and first transparent substrate; a third transparent substrate provided at the outer surface side of at least one of the first transparent substrate and the second transparent substrate; and a first light-shielding partitioning periphery provided at the third transparent substrate to define the display area.
The electronic optical device is enhanced in its dust preventive function against dust because the third transparent substrates are provided on one or both of the outer surfaces (or the sides opposite to the surfaces confronting the liquid crystal) of the first and second transparent substrates. At the same time, the de-focusing function against flaws and dust adhered on the surface of the third transparent substrate is also enhanced in response to the thickness of the third transparent substrate. For example, the de-focusing function is improved as the third transparent substrate becomes thicker. A first light-shielding film defining the display area is provided on the third transparent substrate. Different from the partitioning periphery built in the conventional electronic optical device, the first partitioning periphery (first light-shielding partitioning periphery) can be provided from the contours of the display area to the edge of the transparent substrate. In other words, providing such partitioning periphery does not prevent ultraviolet light irradiation for curing the ultraviolet light curing resin in the seal area. Because the width of the first light-shielding film can be enlarged as described above, the design margin at the opening of the case is possible to be expanded in accordance with the larger width of the first light-shielding film. Further, the overall heat capacity of the electronic optical device is increased by adding the third transparent substrate, also suppressing the temperature increase due to the incident light in the electronic optical device by virtue of the presence of the light-shielding partitioning periphery. The light-shielding performance in the vicinity of the edge of the electronic optical device can be improved by providing the first light-shielding film when this electronic optical device is applied to a projection type display device such as a liquid crystal projector or a transmissive display device using a back light, thereby preventing ghost images of the auxiliary circuits and elements in the panel as described previously.
The electronic optical device is provided with the first light-shielding film in the area surrounding the display area expanded from contours of the display area to edges of the third transparent substrate.
In the electronic optical device, the width of the first transparent substrate can be expanded by a maximum utilization of the third transparent substrate surface without narrowing the display area, since the first light-shielding film is provided at the area surrounding the display area from the contours of the display area to the edge of the third transparent substrate. Accordingly, the design margin in the vicinity of the edge of the electronic optical device can be expanded in response to the enlargement of this width. As a result of especially improved light-shielding performance in the vicinity of the edge of the electronic optical device, ghost images of the auxiliary circuits and elements in the panel can be also prevented.
The electronic optical device is provided with a second light-shielding film provided at one of the first and second transparent substrates to define the display area, wherein the second light-shielding film is provided so that it does not overlap with the area for forming a seal material to be provided between the first and second transparent substrates, along with being provided inside of the area for forming the seal material.
The second light-shielding film provided at one of either the first or the second transparent substrates in the electronic optical device corresponds to the partitioning periphery built in the conventional electronic optical device, wherein the second light-shielding film is provided so that it does not overlap with the area for forming a seal material to be provided between the first and second transparent substrates, along with being provided inside of the area for forming the seal material. Because irradiation of the ultraviolet light is made possible through the gap between the seal material and the partitioning periphery, the area near the edge of the first and second substrate can be sufficiently adhered with the ultraviolet light curing adhesive. Since the first light-shielding film can be formed up to the edge of the transparent substrate as described above without forming the second light-shielding film up to the edge of the transparent substrate, the design margin of the opening of the case can be enlarged by the first light-shielding film without being restricted by the location and width of the second partitioning periphery (second light-shield partitioning periphery).
In the electronic optical device, at least the outer face side of the first light-shielding film is formed of a light reflection film having an OD (Optical Density) value of 2 or more.
In the electronic optical device, at least the outer surface side (the side opposite to the side of the surface opposing the liquid crystal) of the first light-shielding film is formed of a light-reflecting film of, for example, a metallic reflection film such as Al. Therefore, the first light-shielding film serves as a light shielding film along with reflecting the incident light from outside of the third transparent substrate to the peripheral area of the electronic optical device, making it possible to effectively prevent the temperature of the electronic optical device from being increased due to the incident beam as compared with the case when the first light-shielding film is not provided at the third transparent substrate.
In the electronic optical device, at least the inner surface side of the first light-shielding film is formed of a light absorption film having an OD value of 2 or more.
In the electronic optical device, the inner surface side (the side facing to the liquid crystal) of the first light-shielding film is formed of a light absorption film such as, for example, a resist film or a resin film having an OD value of 2 or more. The light absorption film herein refers to a film having a reflection ratio of 20% or less. Consequently, the first light-shielding film serves as a light shielding film along with absorbing the reflection light or multiple reflection light comprising the light reflected from the first and second transparent substrates, the peeled face of the third transparent substrate and the second light-shielding film. Accordingly, the first light-shielding film is able to prevent the multiple reflection light from the transparent substrates and from the film constructing the partitioning periphery from being projected out of the electronic optical device beforehand.
In the electronic optical device, at least the outer surface side of the second light-shielding film is formed of a light absorption film having an OD value of 2 or more.
The outer surface side of the electronic optical device is formed of a light absorbing film such as, for example, a resist film or a resin film having an OD value of 2 or more. Consequently, the second light-shielding film serves as a light-shielding film along with preventing the reflection light and multiple reflection light from being generated by absorbing the incident light from outside of the third transparent substrate to the display area of the electronic optical device, also preventing the multiple reflection light due to the transparent substrates and films comprising the partitioning periphery from projecting out of the electronic optical device.
The electronic optical device is provided with an opening corresponding to the first light-shielding film along with being further provided with a light-shielding case for accommodating the first and second transparent substrates and said third transparent substrate.
In the electronic optical device, the first and second transparent substrates and the third transparent substrate are accommodated (mounted) in a light-shielding case, the opening of the case being provided in accordance with the first light-shielding film. Therefore, the design margin of the opening can be enlarged according to the width of the first light-shielding film.
In the electronic optical device, the third transparent substrate has a thickness of 1.0 mm or more.
Since the third transparent substrate in the electronic optical device has a thickness of about 1.0 mm or more, the de-focusing performance of the third transparent substrate is more improved, besides suppressing the temperature increase owing to the first light-shielding film provided at the third transparent substrate.
In the electronic optical device, the third transparent substrate and one of the first and second transparent substrates in adjoining relation to the third transparent substrate are formed of a material having an approximately the same refractive index with each other.
In the electronic optical device, reflection at the boundary surface between the third transparent substrate and the first or second transparent substrate in adjoining relation thereto can be reduced in accordance with similarity of the refractive index of the materials comprising both of the substrates.
In the electronic optical device, the third transparent substrate and one of the first and second transparent substrates in adjoining relation to the third transparent substrate are adhered with an adhesive having an approximately equal refractive index to the refractive indices of the transparent substrates.
In the electronic optical device, reflection at the boundary between the third transparent substrate and the first or second transparent substrates in adjoining relation to the third transparent substrate can be reduced in accordance with similarities in the refractive index of the materials comprising these transparent substrates and in the refractive index of the adhesive. Such refraction at the boundary can be markedly reduced especially when the substrates are bonded with their planes with the adhesive.
In the electronic optical device, a void space is provided between the third transparent substrate and one of the first and second transparent substrates in adjoining relation to the third transparent substrate.
Since the first or second transparent substrates in adjoining relation to the third transparent substrate are able to radiate heat via the space in the electronic optical device, the heat increment especially in the vicinity of the liquid crystal is possibly suppressed.
In the electronic optical device, a refection preventive film is formed on the outer surface of the third transparent substrate.
The incident light projecting to the outer surface of the third transparent substrate is projected to the liquid crystal through the third transparent substrate only slightly being reflected by virtue of the reflection preventing film in the electronic optical device. Accordingly, the luminous energy loss at the display area can be reduced along with making the display image luminous. Specifically, there is no need for disposing the reflection preventing film at the outer surface side of the transparent substrate when the electronic optical device is mounted.
The projection type device is provided with a electronic optical device having a light source, a condenser system that condenses the light projected from said light source to guide it to the electronic optical device, and a magnifying projection optical system that projects the optically modulated light with the electronic optical device on a projection plane with magnification.
The projection type device is excellent in at least one of the dust-preventing function, de-focusing function and ghost image preventing function as described above along with being provided with the electronic optical device that is able to enlarge the margin of the case opening, thereby realizing a projection type device that is able to display an image with a good image quality.
The electronic optical device is provided with a first transparent substrate in which pixel electrodes are formed in the display region, a second transparent substrate opposing the first transparent substrate, a liquid crystal disposed between the first transparent substrate and second transparent substrate and a third transparent substrate provided at the outer surface side of the transparent substrate of at least one of the first and second substrates, wherein a plurality of micro-lenses are disposed to form a matrix corresponding to respective pixel electrode on the second transparent substrate.
Improvement of efficiency of light utilization as well as the substantial opening ratio of each pixel are possible by virtue of the micro-lenses. Furthermore, since heat absorption of the electronic optical device can be also prevented by the micro-lenses, heat absorption at the electronic optical device can be prevented even if the overall thickness of the electronic optical device has made larger by providing the third substrate.
The projection type device is provided with a electronic optical device having a light source, a condenser optical system for condensing the light projected from the light source to guide it to the electronic optical device, and a magnifying projection optical system for projecting the light optically modulated with the electronic optical device on a projection plane with magnification.
The projection type device is excellent in the dust preventing function, de-focusing function and heat radiation function, realizing a projection type device capable of display of high quality images with a relatively low cost.
These functions and other advantages of the present invention will be made clear by the embodiments to be described hereinafter.